如何将数据传递给Over ViewController的另一个控制器

Question

我想将数据从一个ViewController传递到VC解雇的另一个VC。有可能吗？

我尝试了下一个方法，没有成功：

按钮单击：

self.dismiss(animated: true) { 
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let controller = storyboard.instantiateViewController(withIdentifier: "EditViewController") as! EditViewController
        controller.segueArray = [values]
    }

当EditViewController再次出现时，我的segueArray是nil。

如何将数据从my ViewController传递到解散的EditViewController？

Answer 1

将数据传递回上一个视图控制器的最佳方法是通过代表...从viewController a到B时，将视图控制器a作为代表和ViewWillDisappear方法传递给ViewWillDisappear方法。viewController B，在ViewController A中调用代表方法。协议将有助于定义代表以及先前VC实现的所需方法。这是一个快速示例：

传递数据的协议：

protocol isAbleToReceiveData {
  func pass(data: String)  //data: string is an example parameter
} 

ViewController A：

class viewControllerA: UIViewController, isAbleToReceiveData {
  func pass(data: String) { //conforms to protocol
  // implement your own implementation
   }
  prepare(for: Segue) {
    /** code for passing data **/
    let vc2 = ViewCOntrollerB()  /
    vc2.delegate = self   //sets the delegate in the new viewcontroller 
                          //before displaying
    present(vc2)
  }
}

删除ViewController：

class viewControllerB: UIViewController {
  var delegate: isAbleToReceiveData
  viewWillDisappear {
      delegate.pass(data: "someData") //call the func in the previous vc
  }
}

Answer 2

在"解雇完成"块中，您创建了EditViewController的新实例。我假设另一个EditViewController实例是在导航堆栈中存在的，您需要找到该实例＆amp;将seguearray设置为值。您可以通过通过导航堆栈的ViewControllers进行迭代来实现：

viewController.navigationController?.viewControllers.forEach({ (vc) in
    if let editVC = vc as? EditViewController {
        editVC.segueArray = ....
    }
})

，但我建议使用委托模式，例如：

protocol EditViewControllerDelegate: class {
    func setSegueArray(segues: [UIStoryboardSegue])
}

在viewController(称为" Just just viewController"(中，解雇块是，声明代表属性：

class ViewController: UIViewController {
    weak var delegate: EditViewControllerDelegate?
    ....
}

然后介绍(我假设来自EditViewController(的实例ViewController设置了委托人，例如：

...
if let vc = presentingViewController as? ViewController {
    vc.delegate = self
}

并将EditViewController符合到委托协议，例如：

extension EditViewController: EditViewControllerDelegate {
    func setSegueArray(segues: [UIStoryboardSegue]) {
        // Do the data setting here eg. self.segues = segues
    }
}

Answer 3

检测何时在视图控制器上按下返回按钮，我只使用：

override func didMove(toParentViewController parent: UIViewController?) {
    guard parent == nil else { return } // Back button pressed
    ... // Pass on the info as shown in you example
} // didMoveToParentViewController

Answer 4

通用解决方案：(🔸swift 5.1(

/**
 * Returns a ViewController of a class Kind
 * ## Examples:
 * UIView.vc(vcKind: CustomViewController.self) // ref to an instance of CustomViewController
 */
public static func vc<T: UIViewController>(vcKind: T.Type? = nil) -> T? {
   guard let appDelegate = UIApplication.shared.delegate, let window = appDelegate.window else { return nil }
   if let vc = window?.rootViewController as? T {
      return vc
   } else if let vc = window?.rootViewController?.presentedViewController as? T {
      return vc
   } else if let vc = window?.rootViewController?.children {
      return vc.lazy.compactMap { $0 as? T }.first
   }
   return nil
}

Answer 5

我认为最简单的解决方案是使用完整处理程序：

示例：

class EditViewController {
    let secondController = SecondController()
    
    func showSecondController() {
        secondController.show() { data in
            //
        }
    }
}
class SecondController {
    var completion: ((_ data: Any?) -> Void)?
    
    func show(completion: @escaping (_ data: Any?) -> Void) {
        // Show something
        self.completion = completion
    }
    func dismiss() {
        if let completion = self.completion {
            completion(nil)
        }
    }
}